First Coffee Roasting Attempt

Tonight I roasted my first batch of coffee beans.  They’re darker than I would have liked but I think they’ll be palatable.

My roaster is a bread maker and hot air gun.  I hot-wired the bread machine’s stirring motor to a switch, and for now I simply point the air gun down into the basket.  The dough hook does a great job of keeping the beans agitated so that they evenly roast.  The red toolbox is my temperature controller.  Today I only used it as a thermometer but soon I’ll install a thermocouple inside the bread pan.

The Roasting Setup

Here’s a closer shot of the thermocouple and my advanced mounting method.  It’s positioned such that the tip of the probe is down inside the beans.  It never showed any hint of wanting to come loose so this could be a permanent solution but I’m a tinkerer so I’ll make something more airtight later on.

Temperature Probe

An important step in roasting is rapid cooling after you’ve hit your desired level of roast.  I’m using a pizza pan & fan which worked out just fine.

Cooling Aparatus
Cooling Aparatus

The roast itself went pretty well except it got too hot right after the first crack and I think the second crack happened too soon for me to notice.  I was going to stop the roast when the second crack started but because I hadn’t heard a second set of cracks I kept at it for a bit more and wound up over-roasting the beans.  They looked good towards the end of the cracking, i.e. they had a nice brown color and weren’t too oily; I should have stopped there.

Mine are on the top right
Mine are on the top-right

In this photo my beans are in the top-right canister – too dark as you can see.  The other canister is Alterra’s Black & Tan blend, even its dark beans aren’t as dark as mine.  The bag has the green beans.

Roasting is a smokey affair, especially when you over-do it!  But overall it’s a straightforward process and should be easy enough to get proficient at.  It’s just like baking but in a 8 minutes.

Don't do this indoors


Vacuum Pot Filtration

I’m impressed with the cleanliness of my vacuum pot’s coffee.  It leaves a lot less sediment as compared to french press, and that last swallow is tolerable rather than being nasty.  The reason a vacuum pot leaves less dust in the cup is that the coffee is pulled through a filter bed forrmed by the grounds.

This photo was taken immediately after the kickdown, the dusty scum is clearly visible on the sides of the bowl.

Light-colored dust is visisble on top
Light-colored dust is visible on top

Here I pulled out the rod from the filter bed, you can see how the dust stayed on the top layer.

Layers of dust and clean grounds
Layers of dust and clean grounds

Another shot showing the clean and dirty layers.

The darker, cleaner grounds are visible where the rod was removed
The darker, cleaner grounds are visible where the rod was removed

Compare this to a press pot where the grounds & dust remain suspended in a slurry underneath the plunger.  When pouring a cup the grounds aren’t compacted enough to form a filter bed and the metal screen certainly isn’t going to stop them.

There’s a strong analogy between this and a lauter tun (this is a beer site afterall).  The brewer takes care to form a good filter bed for the lautering process and the grain does most of the work keeping the wort clean.

Cory Vacuum Coffee Pot

Recently I picked up a gasketed Cory vacuum coffee pot off of eBay.  It was “new” in box which was labled “Regent Range”, model DKG-S.  It came with the standard Cory glass filter rod not the “new” one.  The top half is model DRU while the bottom is model DRL.

The gasket was in good shape for a 50 year old piece of rubber; in fact it will had its brown wax paper wrapper.  It was still pliable but not soft enough to seal well, it would not hold a seal during either phase of brewing.  I was able to shove the top down into the bottom but it would soon pop back up after getting warm.  Letting the gasket sit in boiling water for a while only temporarily made it softer.  Eventually I used the transmission leak stop method on the gasket with good results.  My bottle cost $2 at Farm & Fleet.  As long as the gasket is dry it will stay put after shoved into the bottom during both phases.  If the gasket is wet however it does tend to pop back out.  The leak stop fluid didn’t make the gasket more pliable but did make the surface a little more grippy which did the trick for me.  The downside of this method is that your gasket will reek like petroleum for a week.  After treating the gasket I cleaned it with Goo-Gone and then cleaned in dishwater but it will smelled very strongly.  The first pot of coffee I made with it definitely smelled like petroleum.  It’s been a week now and I don’t smell the petrols anymore, but the gasket itself still does have a distinct smell.  I do wish I knew of a better way to recondition these things.

The green line indicates the bottom of the glass tubeThe second thing I did to the pot was to extend the dip tube.  Out of the box the tube leaves a 1″ gap to the bottom of the carafe which in my opinion leaves far too much water, diluting the coffee.  The first pot I made tasted terrible because of all the water, very thin and sour.  I make 16oz batches so the ratio of coffee to water is fairly high.  To fix this I used a short length of 3/4″ ID vinyl tubing and a stainless steel hose clamp to extend the tube.  The extender leaves about a 1/8″ gap which results in just a few ounces of dilution water.  I do take care to use a very low flame during the steeping phase because flame on dry glass will crack it.  I keep the flame just big enough to keep the bubbling going.

My procedure for using my vacuum pot is:

  1. Set aside top half with gasket
  2. Boil water in tea kettle, add to carafe
    1. The kettle is simply faster to heat water than the carafe
  3. Apply heat to the carafe and let the water heat up to 205F
  4. Add grounds to top half and insert, it will start filling right away
  5. Start timer for 4 minutes
  6. Occasionally stir in the floating grounds
  7. Remove from heat

I keep the bowl off of base because it will fill while the water is too cold to properly brew coffee.  With the water naturally rising the grounds/water mixture starts at 178F.  With the water at 205F the slurry winds up at 195F.  I use a steeping time of 4 minutes simply because that’s how long I go with my french press.

overall I like my Cory vacuum pot.  It makes a much cleaner cup than my press and looks nice.  However the dip tube length is a pretty serious design flaw; who wants diluted coffee?  When the gasket seals well the kickdown is very fast and vigorous.